Cajun Blackened Yellowfin Tuna Sliders

     Blackened seafood is not quite as popular as it was in the 1980's and 1990's, but it is still found on menus in many casual seafood restaurants.  The recent trend of gourmet sliders has brought Cajun blackened fish back into the limelight.  Cajun blackened tuna appeals to those who are interested in a slider that is healthier than beef or kobe beef.

     Blackening seafood is an old technique.  The fish is coated with Cajun spices and then seared in butter at a high temperature.  The blackening spice mixture turns black and the flavor of the Cajun spices infuse with the meat.  By searing at a high temperature, the fish filet's juices are also locked into the meat.
     If you are ever served blackened fish that does not have black highlights in a restaurant, then the fish was seared at too low of temperature.
     A chef at the Cordon Bleu cooking school was teaching that blackened food should never be cooked, till black highlights appear.  He also stated that only granulated garlic and granulated dried onion should be used in the blackening spice mixture.  I did not even bother to listen to the teacher during that class, because he was so very wrong.
     I worked for more than 5 years with top of the line Louisiana Cajun chefs and cooks in southern coastal seafood restaurants during the peak of the blackened seafood era.  I used to blacken more than 2 full pallets of fresh redfish each day at my busy saute station at one Cajun restaurant.  Contrary to what the Cordon Bleu teacher said, fish is supposed to be blackened at a high temperature, till black highlights appear on the peaks of the meat grain of fish!
     The second contradiction, that I have in reference to what the Cordon bleu teacher said about granulated onion and garlic, is that they tend to singe and they become a bitter flavor at high temperatures.  Onion powder and garlic powder truly are best for blackening at high temperatures.  I have bit my tongue many times at Cordon Bleu, rather than to correct a Cordon Bleu teacher that is wrong!  I am sure that the same situation occurs with very experienced chef students at every brand of chef school.
     Before the Cajun cayenne spice mixture was used for blackening redfish during the last century, a very different blackening method was used for more than 100 years.  Coarse edible rock salt and very coarsely crushed black peppercorns were pressed firmly into the flesh of a redfish filet.  The redfish filet was then seared in smoking hot butter for 6 minutes on one side and 1 minute on the other side.  Most of the rock salt melted from the moisture of the redfish and it caused the redfish to crust with dark brownish black highlights.  All the flavor of the redfish was sealed in beneath the black crust!  I have only cooked with the original Cajun rock salt black pepper blackened method twice during my career on request.  Both requests came from elderly senior citizens from Louisiana.  I really liked how the original Cajun blackening method turned out!  
     Fish like grouper, snapper, redfish and mahi mahi are some of the best fish to blacken.  Tuna turns out rather dark, because there are far fewer natural juices in tuna meat and the meat grain is very tight.  With fewer juices, the tuna becomes darker even faster.  That is okay, because tuna is usually cooked so that it is rare in the center anyway.
     In the Cajun seafood restaurants that I worked in, we would never blacken tuna, swordfish or any firm textured fish.  We only blackened redfish, grouper, snapper and fresh water catfish.  Those three saltwater fish were the most popular Gulf of Mexico fish.  Unfortunately, because of the lingering effects of the Gulf of Mexico oil spill, I do not promote eating any gulf seafood at this time and I will not suggest eating gulf seafood for many years to come.
   
     Cajun Blackening Spice Mix Recipe:
     Blackening does produce some smoke.  Be sure that the kitchen fan is on and that the kitchen is well ventilated.
     This recipe makes enough Cajun blackening spice for about 5 portion applications.
     The tiny amount of sugar helps to caramelize the highlights of the grains of the fish meat.  The small dash of flour helps the spice mix to stick to the fish.
     This is a basic Cajun blackening spice mix.  Some chefs add many dried herbs to the spice mixture, but it is not necessary.  If you have experience with Cajun herbs, then feel free to customize this basic recipe to your own taste.  Chef Paul Prudhomme adds many Cajun herbs to his blackening spice recipe.  I add Cajun herbs too, when when I am working for a restaurant that is competing with other Cajun restaurants in the area.  For a beginner, it is best to master the basics of a blackening spice mixture, before trying to get fancy!
     Place 1/2 tablespoon of onion powder into a small mixing bowl.
     Add 1/2 tablespoon of garlic powder.
     Add 4 tablespoons paprika.
     Add 4 tablespoons of cayenne pepper.
     Add 1/2 tablespoon of black pepper.
     Add 1 teaspoon of white pepper.
     Add 1/2 tablespoon of sea salt.
     Add 2 teaspoons of sugar.
     Add 2 teaspoons of flour.
     Mix the ingredients together.
   
     Cajun Blackened Yellowfin Tuna Sliders Recipe:   
     Note:  The blackening technique of high temperature searing of 6 minutes on one side and 1 minute on the other side cannot be applied to tuna.  Just blacken till black crusty highlights appear and then flip the fish to blacken the other side. 
     Split 3 slider rolls in half.
     Brush the slider rolls with garlic butter.
     Grill the rolls in a saute pan or griddle over medium/medium low heat, till they become toasted golden brown.
     Place the rolls on a plate.
     Place a cucumber slice on the bottom half of each roll.
     Place some alfalfa sprouts on top of the cucumber slices.
     Cut a thick yellowfin tuna steak into 3 pieces, so that each piece will fit on the slider rolls.  The yellowfin tuna slider portions should weigh about 2 ounces apiece.
     Heat 7 pats of unsalted butter in a cast iron skillet or in a saute pan over medium high heat.
     Heat the butter, till the butter just begins to start smoking.
     Dredge the tuna pieces in the Cajun blackening spice mix.
     Use a pair of tongs to set the Cajun spiced tuna sliders in the smoking hot butter.
     Blacken each side of the fish for about 1 1/2 to 2 minutes.  (Tuna cooks very quickly and you want the tuna sliders to be cooked no more than a medium rare to medium temperature.)
     Only flip the tuna sliders once!
     When the blackened tuna sliders are cooked to the desired temperature, remove them from the pan and let them rest on a dish for 30 seconds.
     Set the blackened tuna sliders on each of the slider roll bottom set ups on the plate.
     Lean the slider roll tops against the tuna sliders.
     Serve with a potato, pickles or vegetables of your choice.  (I served the sliders in the pictures with kimchi.  Why Korean kimchi?  I just happened to have some kimchi on hand and us Cajun cooks like almost anything that is spicy!)
   
     The yellowfin tuna should be rare in the center for the best flavor.  Fully cooked tuna is dry and tough.  Rare to medium temperature tuna is best!
     These are some spicy Cajun blackened yellowfin tuna sliders!  The garlic butter slider rolls add to the appeal.  I have blackened tons of seafood in my life time.  My favorite will always be fresh caught, blackened redfish.  Redfish is now legally listed as a sport fish and it cannot be sold commercially.
     Blackened yellowfin tuna sliders!  Yum!  ...  Shawna